Graphic source: http://www.nih.gov/news/health/nov2012/nci-06.htm This bar graph displays the years of life gained when participants met various percentages of HHS guidelines for physical activity. 50% = 1.8 years. 100% = 3.4 years. 200% = 4.2 years. 300% = 4.5 years. According to November 2012's "NIH study finds leisure-time physical activity extends life expectancy as much as 4.5 years" "Leisure-time physical activity is associated with longer life expectancy, even at relatively low levels of activity and regardless of body weight, according to a study by a team of researchers led by the National Cancer Institute (NCI), part of the National Institutes of Health. The study, which found that people who engaged in leisure-time physical activity had life expectancy gains of as much as 4.5 years.

"The U.S. Department of Health and Human Services,...recommends that adults ages 18 to 64 engage in regular aerobic physical activity for 2.5 hours at moderate intensity or 1.25 hours at vigorous intensity each week. Moderate activities are those during which a person could talk but not sing. Vigorous activities are those during which a person could say only a few words without stopping for breath. After accounting for other factors that could affect life expectancy, the researchers found that life expectancy was 3.4 years longer for people who reported they got the recommend level of physical activity. People who reported leisure-time physical activity at twice the recommended level gained 4.2 years of life. In general, more physical activity corresponded to longer life expectancy." The researchers even saw benefit at low levels of activity. For example, people who said they got half of the recommended amount of physical activity still added 1.8 years to their life. "Our findings highlight the important contribution that leisure-time physical activity in adulthood can make to longevity." said study author Steven Moore, Ph.D., of NCI's Division of Cancer Epidemiology and Genetics, and lead author of the study. Regular exercise extended the lives in every group that we examined in our study normal weight, overweight, or obese. The researchers found that the association between physical activity and life expectancy was similar between men and women, and blacks gained more years of life expectancy than whites. The relationship between life expectancy and physical activity was stronger among those with a history of cancer or heart disease than among people with no history of cancer or heart disease." Citation source: http://www.nih.gov/news/health/nov2012/nci-06.htm